New imines, their preparation and their pharmaceutical use

ABSTRACT

Imines of 2-formylquinoxaline-3-carboxylic acid-1,4-dioxides and their salts are obtained through treatment of the lactone or a salt of 2-dihydroxymethylquinoxaline-N,N-dioxide-3-carboxylic acid with a reactant bearing a free primary amino group. The resultant compounds and their non-toxic salts are antibacterial agents and can be incorporated in pharmaceutical compositions and feedstuffs for this use. A typical embodiment is 2(carbomethoxyhydrazonomethyl)-quinoxaline-3-carboxylic acid-1,4dioxide.

United States Patent [1 1 Seng et al.

[ 51 Nov. 5, 1974 NEW IMINES, THEIR PREPARATION AND THEIR PHARMACEUTICAL USE [75] Inventors: Florin Seng, Colonge-Buchheim;

Kurt Ley, Odenthal-GloBusch;

Georg Metzger, Wuppertal-Elberfeld, all of Germany [73] Assignee: Bayer Aktiengesellschaft [22] Filed: May 11, 1973 21 Appl. No.: 359,279

Related U.S. Application Data [62] Division of Ser. No. 130,007, March 31, 1971 [30] Foreign Application Priority Data Apr. 2, i970 Germany 2015675 [52] U.S. Cl. 260/250 QN, 99/2 M, 99/4,

424/250, 260/250 Q [51] Int. Cl C07d 51/78 [58] Field of Search 260/240 G, 250 Q, 250 ON [56] References Cited UNITED STATES PATENTS 3,371,090 2/1968 Johnston 260/240 G 2/1970 Johnston 260/250 ON 2/1974 Seng et al. 260/250 QN FOREIGN PATENTS OR APPLlCATlONS l,2l5,8l5 l2/l970 England .,260/250Q 7,104,392 l0/l97l Netherlands ..260/250 QN v Primary Examiner.lohn D. Randolph [57] ABSTRACT Vlmines of 2-formylquinoxaline-3-carboxylic acid-1,4- dioxides and their salts are obtained through treat- 14 Claims, No Drawings NEW IMINES, THEIR PREPARATION AND THEIR PHARMACEUTICAL USE This is a division of application Ser. No. 130,007 filed March 31,1971.

The present invention relates to new imines of 2- 5 formylguinoxaline-3-carboxylic acid-1,4-dioxides and their salts, to processes for their preparation, to the use of the new compounds as medicaments in human medicine and veterinary medicine, to their use as feedstuff additives, especially in raising young animals or fatstock, and to compositions adapted to this use.

The new imines and salts have the general formula:

0 III [5 [COOY wherein Y is hydrogen, an alkali metal cation or the cation R Nl-l and each of R and R is identical to or different from the other and is selected from the group consisting of a. alkyl, substituted alkyl or cycloalkyl;

in which each of R and R when taken independently is identical to or different from the other, and is selected from the group consisting of hydrogen, alkyl or substituted alkyl, or when R and R are taken together in which R is alkyl or substituted alkyl;

in which 'R is phenyl, pyridyl or norbornyl, and X is as defined above;

in which R, R and X are as defined above; or

A preferred group of the imines and salts of the invention are those of the above general formula l in which:

Y has the meanings given above;

each of R and R is identical to or different from the other and is selected from the group consisting of a. alkyl or hydroxyalkyl of from one to four carbon atoms or a -membered or 7-membered monocycloor bicycloalkyl group;

in which each of R and R when taken independently is identical to or different from the other and is selected from the group consisting of hydrogen, alkyl or hydroxyalkyl of from one to four carbon atoms, or when R and R are taken together with the nitrogen atom to g which they are attached, a six-membered heterocyclic ring optionally containing as a ring member oxygen or in which X is O, S or NH, and R and R are as herein defined;

in which R is alkyl or hydroxyalkyl of from one to four carbon atoms; and

in which R is phenyl, pyridyl or norbornyl, and X is as herein defined.

Aliphatic groups embraced by R and R include straightchain or branched alkyl groups of from one to six, preferably one to four, carbon atoms. Cycloaliphatic radicals contain from three to seven, preferably five to seven, carbon atoms and include both monocyclic and bicyclic ring systems.

These aliphatic or cycloaliphatic groups can be optionally substituted, for example, by hydroxy, alkoxy, or acyloxy, the alkoxy and acyloxy groups containing one to four, preferably one or two, carbon atoms. The hydroxy group is the preferred substituent. Typical aliphatic and cycloaliphatic groups thus include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert.-butyl, n-pentyl, isopentyl, hexyl, 2-hydroxyethyl, cyclopropyl, cyclopentyl, cyclohexyl, bicyclo-(2,2,l )-heptyl (norbornyl), and the like.

The substituents R and R are hydrogen or alkyl of from one to four, preferably one or two, carbon atoms.

These alkyl groups can be optionally substituted with hydroxy, alkoxy or acyloxy, alkoxy and acyloxy groups containing one to four, preferably one or two, carbon atoms. Thus included are ethyl, n-propyl, isopropyl, nbutyl, isobutyl and tert.-butyl, as well as the corresponding groups substituted by hydroxy.

R and R when taken together with the nitrogen atom to which they are attached, can also form a heterocyclic ring, preferably containing six ring members, and preferably with an oxygen atom, a sulphur atom, an N-alkyl group containing one to four, preferably one or two, carbon atoms, or the S group, as a ring member in the p-position relative to the nitrogen atom to which R and R are attached.

R is an alkyl of from one to four, preferably one or two, carbon atoms which may also be optionally substituted by hydroxy, alkoxy, acyloxy, alkoxy and acyloxy containing one to four, preferably one or two, carbon atoms. The hydroxy group is a particularly preferred substituent. R thus embraces such groups as' methyl, ethyl, Z-hydroxyethyl and the like.

The alkali metal cation Y is, for example, that of sodium or potassium, preferably that of sodium. I

R is phenyl, pyridyl or norborn-2-yl. When R is pyridyl, it can be bonded in the 2-, 3- or 4-position relative to the pyridyl nitrogen atom.

The above class of imines are obtained according to the process of the present invention by treatment of loxo-3-hydroxy-l ,3-dihydro-furo-( 3 ,4-b )-quinoxaline- 4,9-dioxide, which has the formula:

Q rlz 0H 0 $11 or a salt thereof of the formula:

M 0H \N/ ofi J,

OH X

with an amine of'the general formula H N-R, in which R is as previously defined, Mis an alkali metal or alka- Both inorganic and organic polar solvents can be used as diluents for the reaction according to the invention, such as for example water, lower aliphatic alcohols of one to four carbon atoms, lower aliphatic nitriles such as acetonitrile, tetrahydrofurane, dioxane, dimethoxyethane, pyridine, dimethylformamide and the like.

The reaction according to the invention is carried out at a temperature of about 0 C to about 50 C, preferably 20 C to about 35 C.

In practice, the lactone or lactone salts are dissolved or suspended in the diluent, and this solution or suspension is then treated with an appropriate quantity of the amine. The formation of the imine or of the imine salt takes place in a weakly exothermic reaction and the final product is then isolated through conventional methods.

The imine salts (1) can also be prepared by the reaction of the free acids with amines.

The salts may be obtained in a subsequent step by conventional techniques or directly in the reaction of the lactone with the amine. If about 2 mols of the amine per mol of lactone are employed, the product will be in the form of that amine salt. If an alkali metal salt or alkaline earth metal salt of the lactone is employed, or if it is desired to obtain the free acid from the lactone, only about 1 mol of the amine per mol of the lactone or salt is required.

The course of the process according to the invention The following examples will serve to further typify the nature of this invention without being a'limitation on the scope thereof.

EXAMPLE 1 23.4 g (0.1 mol) of l-oxo-3-hydroxy-1,3-dihydrofuro-(3,4-b)-quinoxaline-4,9-dioxide are suspended in 60 ml of water and 20 g (0.2 mol) of 60 percent strength aqueous isopropylamine solution are added. The temperature is kept below 30 C by slight cooling. After a few minutes, a clear solution is produced. Evaporation in vacuo yields 45 g of the compound of the formula in the form of yellow crystals, which after recrystallisation from isopropanol melt at 12314 125 C, with decomposition.

Analysis: C 1-1 N O (molecular weight 334) Calculated: C 57.5% H 6.6% N 16.8% Found: C 57.1% H 5.8% N 16.8%

EXAMPLE 2 27.4 g (0.1 mol) of the Na salt of 2-(di-hydroxymethyl)-3-carboxylic acid-quinoxaline-di-N-oxide are dissolved in 100 ml of water and 7.3 g (0.1 mol) of tert.-butylamine are added. The temperature is kept at 25 C by cooling. After 1 hour, the solution is evaporated in vacuo and 32 g of the compound of the formula are obtained in the form of yellow crystals which after recrystallisation from acetonitrile/water melt at 228 C, with decomposition.

Analysis: C H N NuO (molecular weight 311) Calculated: 54.0% H 4.5% N 13.5% Nu 7.4% l-ountl: 53.7% H 4.9% N 13.5% 116.9%

The l-oxo-3-hydroxyl ,3-dihydro-furo-( 3,4-b)- quinoxaline-4,9-dioxide of the formula (1) required as the starting compound can be obtained as follows:

30.7 g (0.1 mol) of 2-bismethoxy-methyl-3-dimethylaminocarbonyl-quinoxaline-1,4-di-N-oxide are introduced into 100 ml of percent strength aqueous hydrochloric acid. A clear solution results, and after a short time the compound according to the invention separates out in the form of a yellow precipitate, which is filtered off after 6 hours. 17 g (72.6 percent of theory) of l-oxo-3-hydroxy-1,3-dihydro-furo-(3,4-b) quinoxaline-4,9-dioxide are thus obtained in the form of yellow crystals.

. The compound is purified by dissolving it in sodium bicarbonate solution, filtering and acidifying the filtrate. The purified compound melts at 156 159 C, whilst foaming.

Analysis: C H.N,O,-, (235) Calculated: Found:

C5l.3% 2.6% l C 52.0% H 2.8% 12.

Melting Ex. point No. Compound C.)

N e e oooram-orn CH=N-C113 l o 0 -86 T N 9 69 i oooI-I3No2n5 -CH=NO2II5 106 N e e cooling-0.111

N/ C II=N-C3II1 l o O CH; 1 138- 10 T 9 63 e /N COOI-IaN- CH:

1 .Ha (lllla f on N- l:- run (lllll I 12 so e to /N\ ooonm- 1[ f CH=N n o Table l.Continued Melting Ex. point d o MIC my /ml of medium NO Compoun C Compound Compound Compound 9 o 212-213 Bacterium Example Example Example O O OH Klebsiella neumonia 63 I \N N NH C O O CZHS l fletosiella 1 pneumonia 8085 20 0 1O Staphylococcus aureur I33 3O 0 1 156-157 Streptococcus II pvogenes W 100 0 0 OH CH=N-NHCOOCH2CH2OH 15 T able 2 0 Mmimum 1nh1b1tory concentration (MIC) 1n y/ml of 1 Decomposition. medlum, measured by the series dilution test (complete medium), incubation temperature: 37C, determina- As has already been mentioned, the new compounds tion of the MIC after 18, 24 and 48 hours. of the invention surprisingly show an excellent chemotherapeutic activity. Their chemotherapeutic action was examined both in animal experiments (oral and Compound of subcutaneous administration) with acute bacterial in- Bacterium Example 13 fections, and in vitro. In both cases the compounds 25 show a very good antibacterial action, and the range of flfif ATCC 3222 ,8 action encompasses both Gram-negative and Gramg 8538 50 positive bacteria. The chemotherapeutic activity of the g: 32 :88 compounds according to the invention permits their do. 8711 50 use in human medicine and in veterinary medicine. g ATCC g g 9 Furthermore, the compounds can be employed as feed- 13 2 stuff additives, especially in raising young animals or 38- g8 fatstock. The good in vitro and in vivo activity of the a 25 compounds according to the invention can be seen 35 Esvherichfl wli C 3? from Tables I, 2 and 3 below. 3: 55 B 5 The minimum inhibitory concentrations in vitro for do. 14 12-25 some of the new compounds shown in Table l (MIC) 38' 5% 5 were determined by the plate test in an agar medium of Proteus mirabilis G 12 do. 2935 12 the following compos1t1on. 40 do. vulgar 3400 Q 50 proteose peptone 10.0 g per litre p gs 7 veal extract (solids) 10.0 g do. nemginom dextrose 2.0 g do. M 25 sodium chloride 3.0 g do. B 25 gg qg g p g p %-g g 33- Klebsiella ATCC 10031 1-2 I do. K 10 50 adenine sulphate 0.01 g do. 1 3 5() guan ne hydrochlorlde 0.01 g do. S l ll hii BB ll 12 Ufacll 8 Corynebacterium diphteriae gravis 5-10 Xamhm 8 Staphylococcus aureus I33 neutral agar 12.0 g 1 do. 7705 12 I do. BRL 12 5.10 X 10 germs were inoculated per plate. Readings xggg zgggfff 'j N 2 were taken after 24 and 48 hours, and the incuba- Mycaoplasma galliselnticum g 0- granu arum temperature was about 37 Mycobacterium tuberculosis H 37 RV I 40 Table 1 I '1 measured in a PPLO medium MIC in -y/ml of medium Comgtound Comgtound Comgtound For the compound of Example 3, the following mini- Bactefium Example Example Example mal nh bitory concentrauons (MIC) (-y/mlof nutrient 10 12 13 medium). were measured by the series d1lut1on test Escherichia (PPLO medium), incubation temperature 37 C, detercoli A 261 20 mmationafter 18, 24 and 48 hours. Escherichia coli C I 50 Proteus vulgaris species I50 10 65 Preudomonas Bacterium MIC aerugmoxa g loo Mycaplarma gallisepticum I00 I reudoumnas do. granularum 25 r smv do. bovirhinis 200 Walter ill In animal experiments on mice, the effective 100 percent dose (ED in mg/Kg was determined for certain compounds of the invention after intraperitoneal infection and subcutaneous (s.c.) or oral (p.o.) administrament of the invention. The diluents and carriers used are preferably therefore those that adapt the active in-.

gredient or ingredients for oral administration. Examples of such diluents and carriers are solid vehicles, ex-

tion of the preparation. 5 cipients and lubricants such as glucose, lactose and su- Table 3 Compound of Compound of Compound of Compound ol' Bacterium Example 3 Example 8 Example 13 Example 14 s.c. p.o. s.c. p.o. s.c. p.o. s.c. p.o.

Escherichia 50 100 50 100 25 25 50 I coli C I65 Staphylococ- 25 O CUS aureus In general, it has proved advantageous, in acute general infections, to administer amounts of about 5 mg to about 200 mg per kilogram, preferably about 25 to about 50 mg per kilogram of body weight per day, to achieve effective results. Nevertheless it can at times be necessary to deviate from the amounts mentioned, in particular depending on the body weight of the test animal or patient or on the nature of the method of administration, but also because of the type of animal and its individual behaviour towards the medicament, or because of the nature of the formulation of the latter, and the point in time or interval at which administration takes place. Thus it can, in some cases, suffice to use less than the abovementioned minimum amount, whilst in other cases the upper limit mentioned must be exceeded. In the case of the administration of larger amounts it can be advisable to divide these into several individual doses over the course of the day. The same range of dosages is envisaged for administration in human medicine. The other comments made above also apply in a general sense.

Accordingly, the present invention provides a pharmaceutical composition containing'as an active ingredient at least one of the new compounds of the general formula (1) given above in admixture with a pharmaceutically acceptable solid or liquid diluent or carrier as hereinafter define.

In the present specification the expression pharmaceutically acceptable diluent or carrier means a nontoxic substance that when mixed with the active ingredient or ingredients renders it suitable for administration. The expression preferably excludes water and low-molecular weight organic solvents commonly used in chemical synthesis, except in the presence of other pharmaceutically necessary ingredients such as salts in correct quantities to render the composition isotonic, buffers, surfactants, colouring and flavouring agents, and preservatives. Examples of suitable liquid diluents and carriers are vegetable oils, glycerol, propylene glycol, polyols, buffered aqueous solutions, isotonic saline aqueous solutions, syrups and lotion bases. Examples of suitable solid diluents and carriers are starches, cellulose and its derivatives, sugars, stearates and stearic acid, talc, and ointment bases. Examples of pharmaceutical compositions according to the invention are ointments, pastes, creams, sprays, lotions, aqueous and non-aqueous suspensions, emulsions, and solutions (including parenterally injectable solutions), elixirs and syrups, and granulates and powders either free-flowing or compressed into tablets.

Pharmaceutical compositions of the invention adapted for oral administration are a preferred embodicrose, corn and potato starch, sodium carboxymethylcellulose, ethyl cellulose and cellulose acetate, powdered gum tragacanth, gelatin, alginic acid, agar, talc, stearic acid and sodium, calcium and magnesium stearates, sodium lauryl sulphate, polyvinyl-pyrollidone, sodium citrate, calcium carbonate, and dicalcium phosphate.

The pharmaceutical compositions of the invention may also contain other non-toxic adjuvants and modifiers such as dyes, surfactants, perfumes, flavouring agents, such as sweeteners, preservatives and biocides.

Pharmaceutical compositions of the invention adapted for parenteral injection are another preferred embodiment of the invention. The diluents and carriers used are therefore preferably those that adapt the active ingredient for parenteral administration. Examples of diluents and carriers that adapt the active ingredient for parenteral administration are solvents and suspending diluents such as water, vegetable fatty oils, such as sesame oil, groundnut oil, corn oil, and cottonseed oil,

aqueous propylene glycol, N,N'-dimethylformamide, and dimethyl sulphoxide. In general, any non-aqueous diluent can be used that does not reduce the activity of the active ingredient and is non-toxic in the dose employed.

For the administration of the water-soluble com pounds of the invention by parenteral injection sterile aqueous solutions can be employed, and are within the scope of the pharmaceutical compositions of the invention. Such aqueous solutions should preferably when necessary be buffered in the usual manner, and the liquid diluent should preferably before administration be rendered isotonic by adding the requisite amount of salt or glucose. Such sterile buffered isotonic solutions are especially suitable for intravenous, intramuscular and intraperitoneal injections. These pharmaceutical compositions of the invention can further contain local anaesthetics or substances that promote the diffusion of the active ingredient, for example hyaluronidase.

The pharmaceutical compositions of the invention preferably contain 0.5 to wt. percent of at least one new compound of the invention.

The present invention also provides medicaments in dosage unit form as hereinafter defined comprising as an active ingredient at least one compound of general formula (1) given above eitheralone or in admixture with a pharmaceutically acceptable solid or liquid diluent or carrier. In this case the diluent or carrier is preferably as defined above but can also be water or another common solvent.

The expression medicament in dosage unit form as used in the present specification means a medicament in the form of discrete portions each containing a unit dose or a multiple or sub-multiple of a unit dose of the active ingredient(s); for example, one, two, three or four unit doses or a half, a third or a quarter of a unit dose. A unit dose is the amount of the active ingredient(s) to be administered on one occasion and will usually be a daily dose, or for example a half, a third, or a quarter of a daily dose depending on whether the medicament is to be administered once or, for example, twice, three times, or four times a day.

The discrete portions constituting the medicament in dosage unit form can include a protective envelope. The active ingredient can be undiluted and contained in such an envelope, or can be mixed with a pharmaceutically acceptable solid or liquid diluent or carrier as defined above. Such portions can for example be in monolithic coherent form, such as tablets, lozenges, pastilles, pills, suppositories, or dragees; in wrapped or concealed form, the active ingredients being within a protective envelope, such as wrapped powders, cachets, sachets, capsules, or ampoules; or in the form of a sterile solution suitable for parenteral injection, such as ampoules of buffered, isotonic, sterile, pyrogen-free aqueous solution; or in any other form known in the art.

As stated above, peroral administration is a preferred mode of administration. Preferred medicaments in dosage unit form according to the invention are therefore those adapted for oral administration, such as tablets, pills, dragees, capsules, and cachets, as well as wrapped powders containing the active ingredient in powdered form with a powdered diluent or carrier for suspension in water before being taken.

As also stated above a further preferred mode of administration is parenteral administration. Preferred medicaments in dosage unit form according to the invention are therefore those adapted for parenteral injection, such as ampoules containing a measured quantity of a sterile isotonic saline injectable aqueous solution of the new active ingredient, which may be buffered with a pharmaceutically acceptable buffer and are preferably free of pyrogens.

The preferred unit dose for administration of the medicaments of the invention is 250 16,000 mg. of active ingredient, preferably 1,250 4,000 mg. This will usually be administered once daily.

The invention further provides a method of combatting bacterial infection in an animal which comprises administering to the animal (preferably parenterally or perorally) an effective amount of one of the new com-- pounds, either alone, as a pharmaceutical composition according to the invention, or as a medicament in dosage unit form according to the invention.

Indications envisaged in human medicine are especially general infections, and infections of the efferent urinary tract, caused by Gram-positive and Gramnegative bacteria and by mycoplasma, and in veterinary medicine are general infections caused by Gramnegative and Gram-positive bacteria and by mycoplasma. Infections of the respiratory passages in poultryyespecially in chicks, and mastitis of cows, may be i mentioned particularly.

The new compounds can, as has already been mentioned, also be employed as a feedstuff additive, .predominantly in raising young animals, especially chicks and fatstock.

The preparations can be administered in the feedstuff, special feedstuff preparations and feedstuff concentrates, but also via the drinking water.

The invention therefore also provides animal feedstuffs and feedstuff concentrates containing at least one of the new compounds of general formula (1).

The administration of the new compounds together with the feedstuff or feedstuff preparations and/or with the drinking water makes it possible to prevent or treat infections by both Gram-negative andGram-positive bacteria and mycoplasma, and can furthermore contribute to better utilisation of the feedstuff. As examples of frequently occurring veterinary illnesses which cause considerable economic damage and which can be prevented or treated by administering the new compounds in the feedstuff or in the drinking water, there may be mentioned, in addition to general infections, infection of the air sac in chicks, and mastitis in cows.

What is claimed is: l. A compound of the formula:

' or a pharmaceutically acceptable non-toxic salt thereof wherein p Y is hydrogen, an alkali metal cation or the cation R--, Nl-l and each of R and R is wherein R is alkyl of one to four carbon atoms or hydroxyalkyl of one to four carbon atoms.

2. A compound according to claim 1 wherein the alkyl group and the hydroxyalkyl group have one or two carbon atoms. I

3. A compound according to claim 1 wherein R is alkyl of one to four carbon atoms.

4. A compound according to claim 1 wherein R is alkyl of 0mm two carbon atoms.

or a pharmaceutically acceptable non-toxic alkali metal or alkaline earth metal salt thereof.

15 l6 7 10. The compound according to claim 1 which is 13. The compound according to claim 1 which is T /N\\ COONa T r I oo011 CH=NNHOOOCH3 N CH=N-NHC 0 0 02m \N 11. Th e compound according to claim 1 which is O 0 W c a... Vc-.,. ...v i

10 /1I1\ or a pharmaceutlcally acceptable non-toxic alkali 1 metal or alkaline earth metal salt thereof.

\N/ l o 14. The compound according to claim 1 which is CH'=N-NHCOOC2H5 o 12. The compound according to claim 1 which is 1;

H v COOH v p 000m N J-CH=NNHC0OCHzCHzOH 0 1 ll 0 \N/ CH=I\ IN-H-C( )CH2CH20H I 

1. A COMPOUND OF THE FORMULA:
 2. A compound according to claim 1 wherein the alkyl group and the hydroxyalkyl group have one or two carbon atoms.
 3. A compound according to claim 1 wherein R3 is alkyl of one to four carbon atoms.
 4. A compound according to claim 1 wherein R3 is alkyl of one or two carbon atoms.
 5. A compound according to claim 1 wherein R3 is hydroxyalkyl of one to four carbon atoms.
 6. A compound according to claim 1 wherein R3 is hydroxyalkyl of one or two carbon atoms.
 7. A compound according to claim 1 wherein Y is hydrogen.
 8. A compound according to claim 1 wherein Y is a sodium or potassium cation.
 9. The compound according to claim 1 which is
 10. The compound according to claim 1 which is
 11. The compound according to claim 1 which is
 12. The compound according to claim 1 which is
 13. The compound according to claim 1 which is
 14. The compound according to claim 1 which is 